Examples of polymerase in the following topics:
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- RNA Polymerase II (RNAPII) transcribes the major share of eukaryotic genes, so this section will mainly focus on how this specific polymerase accomplishes elongation and termination.
- RNA Polymerase II is a complex of 12 protein subunits.
- The RNA Polymerase travels along the template DNA one nucleotide at at time.
- RNA Polymerase II has no specific signals that terminate its transcription.
- FACT removes two of the histones from the nucleosome immediately ahead of RNA Polymerase, loosening the packaging so that RNA Polymerase II can continue transcription.
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- Transcription elongation begins with the release of the polymerase σ subunit and terminates via the rho protein or via a stable hairpin.
- The transcription elongation phase begins with the release of the σ subunit from the polymerase.
- Near the end of the gene, the polymerase encounters a run of G nucleotides on the DNA template and it stalls.
- As a result, the rho protein collides with the polymerase.
- As the polymerase nears the end of the gene being transcribed, it encounters a region rich in C–G nucleotides.
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- Instead of a single polymerase comprising five subunits, the eukaryotes have three polymerases that are each made up of 10 subunits or more.
- RNA polymerase I synthesizes all of the rRNAs except for the 5S rRNA molecule.
- RNA polymerase III is also located in the nucleus.
- Not all miRNAs are transcribed by RNA Polymerase II, RNA Polymerase III transcribes some of them.
- A generalized promoter of a gene transcribed by RNA polymerase II is shown.
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- Prokaryotes use the same RNA polymerase to transcribe all of their genes.
- In E. coli, the polymerase is composed of five polypeptide subunits, two of which are identical.
- Four of these subunits, denoted α, α, β, and β', comprise the polymerase core enzyme.
- The polymerase comprised of all five subunits is called the holoenzyme.
- The σ subunit dissociates from the polymerase after transcription has been initiated.
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- RNA polymerase binds to the transcription initiation complex, allowing transcription to occur.
- Once this transcription initiation complex is assembled, RNA polymerase can bind to its upstream sequence.
- When bound along with the transcription factors, RNA polymerase is phosphorylated.
- A generalized promoter of a gene transcribed by RNA polymerase II is shown.
- RNA polymerase II then binds and forms the transcription initiation complex.
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- Prokaryotic DNA is replicated by DNA polymerase III in the 5' to 3' direction at a rate of 1000 nucleotides per second.
- In prokaryotes, three main types of polymerases are known: DNA pol I, DNA pol II, and DNA pol III.
- DNA polymerase can only extend in the 5' to 3' direction, which poses a slight problem at the replication fork.
- DNA polymerase III uses this primer to synthesize the daughter DNA strand.
- DNA polymerase I replaces the RNA primer with DNA.
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- This process will continue until the DNA polymerase reaches the end of the template strand.
- All newly synthesized polynucleotide strands must be initiated by a specialized RNA polymerase called primase.
- DNA polymerase can only synthesize new strands in the 5' to 3' direction.
- DNA polymerase halts when it reaches a section of DNA template that has already been replicated.
- An RNA primer is synthesized by primase and is elongated by the DNA polymerase.
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- Most mistakes during replication are corrected by DNA polymerase during replication or by post-replication repair mechanisms.
- DNA replication is a highly accurate process, but mistakes can occasionally occur as when a DNA polymerase inserts a wrong base.
- Most of the mistakes during DNA replication are promptly corrected by DNA polymerase which proofreads the base that has just been added .
- The polymerase checks whether the newly-added base has paired correctly with the base in the template strand.
- Thus, DNA polymerase is able to remove the incorrectly-incorporated bases from the newly-synthesized, non-methylated strand.
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- As DNA polymerase alone cannot replicate the ends of chromosomes, telomerase aids in their replication and prevents chromosome degradation.
- Enzymes RNase H and FEN1 remove RNA primers, but DNA Polymerase will add new DNA only if the DNA Polymerase has an existing strand 5' to it ("behind" it) to extend.
- Once the 3' end of the lagging strand template is sufficiently elongated, DNA polymerase adds the complementary nucleotides to the ends of the chromosomes; thus, the ends of the chromosomes are replicated.
- DNA Polymerase and Ligase will replace all the RNA primers with DNA except the RNA primer at the 5' ends of each newly-synthesized (blue) strand.
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- The DNA can be replicated by the DNA polymerase enzyme.
- Polymerase chain reaction (PCR) is a technique used to amplify specific regions of DNA for further analysis .
- Polymerase chain reaction, or PCR, is used to amplify a specific sequence of DNA.
- Primers—short pieces of DNA complementary to each end of the target sequence—are combined with genomic DNA, Taq polymerase, and deoxynucleotides.
- Taq polymerase is a DNA polymerase isolated from the thermostable bacterium Thermus aquaticus that is able to withstand the high temperatures used in PCR.